Flexible imaging member seam treatment apparatus

ABSTRACT

A belt seam treatment apparatus includes a support element with a smooth surface that supports the seam region of the belt, a heat source that heats a treatment strip and the belt seam region, and a pressure applicator that forces the treatment strip against the belt seam region. The support element can be a tube over which the belt hangs and can include a vacuum belt hold system that secures the seam region against the tube during treatment. The heat source can be an infrared laser or an infrared lamp. Optics form a heat spot or a heat line on the strip and seam region, and a pressure wheel traverses the seam region after heating to compress the strip and seam and bond a thermoplastic polymer of the strip to the seam region of the belt.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related to U.S. patent application Ser. No.10/063,971, now U.S. Pat. No. 6,740,182 issued May 25, 2004, entitledIMPROVED FLEXIBLE IMAGING MEMBER SEAM TREATMENT, U.S. patent applicationSer. No. 10/063,973, entitled FLEXIBLE IMAGING MEMBER SEAM TREATMENTARTICLE AND PREPARATION METHOD THEREOF, and U.S. patent application Ser.No. 10/063,974, entitled FLEXIBLE IMAGING MEMBER SEAM TREATMENTAPPARATUS, all filed on 29 May 2002 herewith, the disclosures of whichare hereby incorporated by reference in their entirety. In addition,this application is related to U.S. patent application Ser. No.09/428,932, filed on 28 Oct. 1999 in the names of Yu et al. and entitledSEAM STRESS RELEASE AND PROTRUSIONS ELIMINATION PROCESS, now U.S. Pat.No. 6,652,691, issued Nov. 25, 2003, the entire disclosure of which isincorporated herein by reference.

BACKGROUND AND SUMMARY

Flexible electrostatographic belt imaging members are well known in theart. Typical electrostatographic flexible belt imaging members include,for example, photoreceptors for electrophotographic imaging systems,electroreceptors such as ionographic imaging members for electrographicimaging systems, and intermediate image transfer belts for transferringtoner images in electrophotographic and electrographic imaging systems.These belts are usually formed by cutting a rectangular, a square, or aparallelogram shape sheet from a web containing at least one layer ofthermoplastic polymeric material, overlapping opposite ends of thesheet, and joining the overlapped ends together to form a welded seam.The seam extends from one edge of the belt to the opposite edge.Generally, these belts comprise at least a supporting substrate layerand at least one imaging layer comprising thermoplastic polymeric matrixmaterial. The imaging layer as employed herein is defined as and refersto any of the dielectric imaging layer of an electroreceptor belt, thetransfer layer of an intermediate transfer belt, and the chargetransport layer of an electrophotographic belt. Thus, the thermoplasticpolymeric matrix material in the imaging layer is generally located inthe upper portion of a cross section of an electrostatographic imagingmember belt, the substrate layer being in the lower portion of the crosssection of the electrostatographic imaging member belt. Although theflexible belts of interest include the mentioned types, for simplicityreasons, the discussion hereinafter will be focus on theelectrophotographic imaging member belts.

Between the substrate and imaging layers, such flexibleelectrophotographic imaging members or multilayered photoreceptors alsotypically include an electrically conductive layer, an optional holeblocking layer, an adhesive layer, a charge generating layer, and, insome embodiments, an anti-curl backing layer. One type of multilayeredphotoreceptor comprises a layer of finely divided particles of aphotoconductive inorganic compound dispersed in an electricallyinsulating organic resin binder to form a layer that is chargegenerating and charge transporting. A typical layered photoreceptorhaving separate charge generating (photogenerating) and charge transportlayers is described in U.S. Pat. No. 4,265,990, the entire disclosurethereof being incorporated herein by reference. In negatively-chargedvarieties of such photoreceptors, a charge generating layer is capableof photogenerating holes and injecting the photogenerated holes into thecharge transport layer.

Although excellent toner images can be obtained with multilayered beltphotoreceptors, it has been found that as more advanced, higher speedelectrophotographic copiers, duplicators and printers are developed,fatigue-induced cracking of the charge transport layer at the weldedseam area is frequently encountered during photoreceptor belt cycling.Moreover, the onset of seam cracking has also been found to rapidly leadto seam delamination due to fatigue, shortening belt service life.Dynamic fatigue seam cracking can possibly happen in ionographic imagingmember belts as well.

As mentioned above, flexible electrostatographic imaging members aretypically fabricated from a sheet cut from an imaging member web,generally in a rectangular or parallelogram shape, and a sheet is formedinto a belt by joining overlapping opposite marginal end regions of thesheet. A seam is typically produced in the overlapping marginal endregions at the point of joining. Joining can be effected by any suitablemeans, such as by welding (including ultrasonic), gluing, taping,pressure heat fusing, and the like. Ultrasonic welding is generally thepreferred method of joining because it is rapid, clean (no solvents),and produces a thin and narrow seam. In addition, ultrasonic welding ispreferred because the mechanical pounding of the welding horn causesgeneration of heat at the contiguous overlapping end marginal regions ofthe sheet to maximize melting of one or more layers therein. A typicalultrasonic welding process is carried out by holding down the overlappedends of a flexible imaging member sheet with vacuum against a flat anvilsurface and guiding the flat end of an ultrasonic vibrating horntransversely across the width of the sheet, over and along the length ofthe overlapped ends, to form a welded seam.

When ultrasonically welded into a belt, the seam of multilayeredelectrophotographic imaging flexible members can occasionally containundesirable high protrusions such as peaks, ridges, spikes, and mounds.These seam protrusions present problems during image cycling of the beltmachine because they interact with cleaning blades to cause blade wearand tear, which ultimately affects cleaning blade efficiency and servicelife. Moreover, the protrusion high spots in the seam can also interferewith the operation of subsystems of copiers, printers and duplicators bydamaging electrode wires used in development subsystems that positionthe wires parallel to and closely spaced from the outer imaging surfaceof belt photoreceptors. These closely spaced wires are employed tofacilitate the formation of a toner powder cloud at a development zoneadjacent to a toner donor roll and the imaging surface of the beltimaging member. Another frequently observed mechanical failure in theimaging belts during image cycling is that, after being subjected toextended bending and flexing cycles over small diameter belt supportrollers, the ultrasonically welded seam of an electrophotographicimaging member can develop cracks that propagate and lead todelamination of the belt. Additionally, such cracking and delaminationcan result from lateral forces caused by mechanical rubbing contactagainst stationary web edge guides of a belt support module duringcycling. Seam cracking and delamination is further aggravated when thebelt is employed in electrophotographic imaging systems utilizing bladecleaning devices and some operational imaging subsystems. Alteration ofmaterials in the various photoreceptor belt layers such as theconductive layer, hole blocking layer, adhesive layer, charge generatinglayer, and/or charge transport layer to suppress cracking anddelamination problems is not easily accomplished. The alteration of thematerials can adversely impact the overall physical, electrical,mechanical, and other properties of the belt such as well as coatinglayer uniformity, residual voltage, background, dark decay, flexibility,and the like.

As mentioned above, when a flexible imaging member used in anelectrophotographic machine is a photoreceptor belt fabricated byultrasonic welding of overlapped opposite ends of a sheet, theultrasonic energy transmitted to the overlapped ends melts thethermoplastic sheet components in the overlap region to form a seam. Theultrasonic welded seam of a multilayered photoreceptor belt isrelatively brittle and low in strength and toughness. The joiningtechniques, particularly the welding process, can result in theformation of a splashing that projects out from either side of the seamin the overlap region of the belt. The overlap region and splashings oneach side of the overlap region comprise a strip from one edge of thebelt to the other that is referred herein as the seam region. The seamregion of a typical overlap seamed flexible belt is about 1.6 timesthicker than the thickness of the body of the belt. Because of thesplashing, a typical flexible imaging member seamed belt has a peaksplashing height of about 76 micrometers above the surface of theimaging layer at the junction between the top splashing and the surfaceof the belt. The junction meeting point is the undesirable site ofphysical discontinuity which has been found to act as astressconcentration point that facilitates early onset of seamcracking/delamination under the dynamic fatigue-inducing conditions towhich imaging members are subjected in normal use.

The photoreceptor belt in an electrophotographic imaging apparatusundergoes bending strain as the belt is cycled over a plurality ofsupport and drive rollers. The excessive thickness of the photoreceptorbelt in the seam region due to the presence of the splashing results ina large induced bending strain as the seam travels over each roller.Generally, small diameter support rollers are highly desirable forsimple, reliable copy paper stripping systems in electrophotographicimaging apparatus utilizing a photoreceptor belt system operating in avery confined space. Unfortunately, small diameter rollers, e.g., lessthan about 0.75 inch (19 millimeters) in diameter, raise the thresholdof mechanical performance criteria to such a high level thatphotoreceptor belt seam failure can become unacceptable for multilayeredbelt photoreceptors. For example, when bending over a 19 millimeterdiameter roller, a typical photoreceptor belt seam splashing can developa 0.96 percent tensile strain due to bending. This is 1.63 times greaterthan a 0.59 percent induced bending strain that develops within the restof the photoreceptor belt. Therefore, the 0.96 percent tensile strain inthe seam splashing region of the belt represents a 63 percent increasein stress placed upon the seam splashing region of the belt.

Under dynamic fatiguing conditions, the seam provides a focal point forstress concentration and becomes the point of crack initiation which isfurther developed into seam delamination causing premature mechanicalfailure in the belt. Thus, the splashing tends to shorten the mechanicallife of the seam and service life of the flexible member belts used incopiers, duplicators, and printers.

Although a solution to suppress the seam cracking/delamination problemshas been successfully demonstrated, as described in a prior art, by aspecific heat treatment process of a flexible electrophotographicimaging member belt with its seam parked directly on top of a 19 mmdiameter back support rod for stress-releasing treatment at atemperature slightly above the glass transition temperature (T_(g)) ofthe charge transport layer of the imaging member, nevertheless this seamstress release process was also found to produce various undesirableeffects such as causing seam area imaging member set and development ofbelt ripples in the active electrophotographic imaging zones of the belt(e.g., the region beyond about 25.2 millimeters from either side fromthe midpoint of the seam). Moreover, the heat treatment can induceundesirable circumferential shrinkage of the imaging belt. The set inthe seam area of an imaging member mechanically adversely interacts withthe cleaning blade and impacts cleaning efficiency. The ripples in theimaging member belt manifest themselves as copy printout defects.Further, the heat induced imaging belt dimensional shrinkage alters theprecise dimensional specifications required for the belt. Another keyshortcoming associated with the prior art seam stress release heattreatment process is the extensive heat exposure of a large seam area.This extensive heat exposure heats both the seam area of the belt aswell as the rod supporting the seam. Since the belt must be cooled tobelow the glass transition temperature of the thermoplastic material inthe belt prior to removal from the support rod to produce the desireddegree of seam stress release in each belt, the heat treatment andcooling cycle time is unduly long and leads to very high belt productioncosts. Additionally, such seam heat treatment stress-release processingdoes not produce the desired seam surface smoothing and protrusion spotelimination.

Since there is no effective way to prevent the generation of localizedhigh protrusions at the seam, imaging member belts are inspected, rightafter seam welding belt production process, manually by hand wearing acotton glove through passing the index finger over the entire seamlength and belts found catching the glove by the protrusions areidentified as production rejects. Both the time consuming procedure ofmanual inspection and the number of seamed belts rejected due to thepresence of high seam protrusions constitute a substantial financialburden on the production cost of imaging members.

The following references may be of interest: U.S. Pat. No. 5,190,608,issued 2 Mar. 1993 to Darcy et al., discloses a flexible belt having anoutwardly facing surface, a welded seam having irregular protrusion onthe outwardly facing surface and a thin flexible strip laminated andcovering the welded seam and protrusions. This belt can be fabricated byproviding a flexible belt having an outwardly facing surface and awelded seam having irregular protrusions on the outwardly facing surfaceand laminating a thin flexible strip to the welded seam. The belt can beused in an electrostatographic imaging process.

U.S. Pat. No. 5,549,999, issued 27 Aug. 1996 to Swain et a., discloses aprocess for coating flexible belt seams including providing a flexiblebelt having an outwardly facing surface and a welded seam, forming asmooth liquid coating comprising a hardenable film forming polymer onthe welded seam, the coating being substantially free of fugitivesolvent, and hardening the coating to form a smooth solid coating on theseam.

U.S. Pat. No. 5,582,949, issued 10 Dec. 1996 to Bigelow et al.,discloses a process for coating flexible belt seams including providinga flexible belt having an outwardly facing surface and a welded seam,forming a smooth liquid coating on the welded seam, the liquid coatingcomprising a film forming polymer and a fugitive liquid carrier in whichthe belt surface is substantially insoluble, and removing the fugitiveliquid carrier to form a smooth solid coating on the seam.

U.S. Pat. No. 6,328,922 B1, issued 11 Dec. 2001 to Mishra et al.,discloses a process for post treatment of an imaging member beltincluding providing a support member having a smooth flat surface,proving a flexible belt having a welded seam, supporting the innersurface of the seam on the smooth flat surface, contacting the seam witha heated surface, heating the seam region with the heated surface toraise the temperature in the seam region to a temperature of from about2° C. to 20° C. about the T_(g) of the thermoplastic polymer material,and compressing the seam with the heated surface with sufficientcompression pressure to smooth out the seam.

U.S. Pat. No. 5,552,005, issued 3 Sep. 1996 to Mammino et al., disclosesa flexible imaging sheet and a method of constructing a flexible imagingsheet. The method of constructing a flexible imaging sheet comprisesoverlapping, joining, and shaping first and second marginal end regionsof a sheet to form an overlap region and a non-overlap region joined toone another by a seam in the overlap region with a generally planarsurface co-planar with a surface of the non-overlap region. The firstand second marginal end regions are secured to one another in theoverlap region by the seam, and are substantially co-planar to minimizestress on the flexible imaging sheet. Minimization of stressconcentration, resulting from dynamic bending of the flexible imagingsheet during cycling over a roller within an electrophotographic imagingapparatus, is particularly accomplished in the present invention.

U.S. Pat. No. 6,074,504 to Yu et al., issued 13 Jun. 2000, discloses aprocess for treating a seamed flexible electrostatographic imaging beltincluding providing an imaging belt having two parallel edges, the beltcomprising at least one layer comprising a thermoplastic polymer matrixand a seam extending from one edge of the belt to the other, the seamhaving an imaginary centerline, providing an elongated support memberhaving at arcuate supporting surface and mass, the arcuate surfacehaving at least a substantially semicircular cross section having aradius of curvature of between about 9.5 millimeters and about 50millimeters, supporting the seam on the arcuate surface with the regionof the belt adjacent each side of the seam conforming to the arcuatesupporting surface of the support member, precisely traversing thelength of the seam from one edge of the belt to the other with thermalenergy radiation having a narrow Gaussian wavelength distribution ofbetween about 10.4 micrometers and about 11.2 micrometers emitted from acarbon dioxide laser, the thermal energy radiation forming a spotstraddling the seam during traverse, the spot having a width of betweenabout 3 millimeters and about 25 millimeters measured in a directionperpendicular to the imaginary centerline of the seam, and rapidlyquenching the seam by thermal conduction of heat from the seam to themass of the support member to a temperature below the glass transitiontemperature of the polymer matrix while the region of the belt adjacenteach side of the seam conforms to the arcuate supporting surface of thesupport member.

While these and other innovative prior art approaches provided improvedflexible belt seam morphology, nevertheless it has been found thatsolution of one problem has also created new undesirable issues. Forexample, overcoating the seam of a photoreceptor belt with metallic foilcan cause electrical seam arcing as the belt cycles beneath a chargingdevice during electrophotographic imaging processes. Additionally,application of liquid overcoating layer over the seam induced chargetransport molecule crystallization in the vicinity of the seam overcoat,not to mention that liquid overcoating layer can produce poor adhesionbond strength to the seam after solidification into a dried coat. Thus,there is a continuing need for electrostatographic imaging belts havingimproved welded seam design that is resistant to seamcracking/delamination, substantially free of seam protrusions, hasimproved seam region physical continuity, and is substantially free offactors that damage imaging subsystems.

Furthermore, there is an urgent need to provide seamed flexible imagingbelts with an improved seam morphology which can withstand greaterdynamic fatigue conditions thereby extending belt service life. It isalso important, from the imaging member belt production point of view,that effective cutting of unit manufacturing cost of seamed imagingbelts can be realized if an innovative post seaming treatment processcan be developed and adopted for belt finishing implementation toprovide the improvement of morphological seam surface smoothing free ofprotrusion spots and to effect the elimination of physical discontinuityat the junction meeting point where the top seam splashing makingcontact with the belt surface.

Embodiments of the instant invention provide such an improvedelectrostatographic imaging member that substantially overcomes theabove-noted deficiencies by providing a morphologically improved seamedelectrostatographic imaging member. Embodiments yield an improvedelectrostatographic imaging member with an ultrasonically welded seamwhich, after being subjected to post processing, exhibits greaterresistance to onset of dynamic fatigue induced seamcracking/delamination problem. After being subjected to post processingaccording to embodiments, seams exhibit good circumferential dimensiontolerance, robust mechanical seam function, and reduced cleaning bladewear. Seams treated according to embodiments are substantially free ofseam protrusions, have smoother surface morphological profiles, havelittle or no seam region physical discontinuity, and have reduced seamarea thickness that greatly reduces seam region bending stress when theelectrostatographic imaging member flexes over small-diameter beltmodule support rollers.

These results are achieved according to embodiments by, for example,providing a flexible belt seam treatment apparatus comprising a supportelement with a smooth surface arranged to support a belt seam region, aheat source comprising an infrared radiation source in opticalcommunication with optics that form a heat spot across at least aportion of a treatment strip and at least a portion of a belt seamregion on which the treatment strip is placed, and a pressure applicatorarranged to force at least the portion of the treatment strip againstthe portion of the belt seam region. The smooth surface can be abhesiveand can include a fluoropolymer. The pressure applicator can include apressure wheel and should exert from about 1 lb/in to about 20 lb/inline contact force. The support element can be substantially planar, inwhich case the pressure wheel has a substantially right cylindricalouter surface, or the support element can be substantially tubular, inwhich case the pressure wheel has a substantially concave outer surfacesubstantially corresponding to an arcuate section of a cross section ofthe support element. Additionally, the outer surface of the pressurewheel can comprise an abhesive coating.

Such results can also be achieved according to embodiments by, forexample, providing a flexible belt seam treatment apparatus comprising asupport element with a smooth surface arranged to support a belt seamregion, a heat source arranged to heat at least a portion of a treatmentstrip to a temperature falling in a range of from about 20° C. to about70° C. above a glass transition temperature of at least one of athermoplastic polymer of the treatment strip and a thermoplastic polymerof the belt seam region, and a pressure applicator arranged to force atleast the portion of the treatment strip against the portion of the beltseam region. The heat source can an incandescent lamp, a high intensitydischarge lamp, a laser, or other suitable infrared radiation source.Optics can arranged to direct infrared radiation from the heat source atthe seam region, such as in a line of infrared radiation across theentire treatment strip and seam region, or in a spot of infraredradiation across a portion of each of the treatment strip and the seamregion.

Such results can further be achieved according to embodiments by, forexample, providing a belt seam treatment apparatus comprising a tubewith a smooth, abhesive outer surface, a belt hold system arranged tohold a seam region of a belt against at least a portion of the outersurface of the tube, an infrared radiation source in opticalcommunication with the at least a portion of the outer surface of thetube against which the seam region of the belt is held, and a pressurewheel with a substantially concave outer surface substantiallycorresponding to a curvature of the at least a portion of the outersurface of the tube against which the seam region of the belt is held.The infrared radiation source can be an infrared laser, and can haveoptics that alter a polarization of infrared radiation from the infraredlaser and form a heat spot on a portion of the seam region of the beltafter a treatment strip has been applied. Further, an actuator can beincluded that adjusts the optics so that the heat spot traverses a widthof the seam region, and/or another actuator that moves the pressurewheel with the heat spot to compress a portion of the strip and the seamregion that the heat spot has heated. Alternatively, the infraredradiation source can be an infrared lamp, and optics can be includedthat reflect and focus the infrared radiation from the infrared lamponto at least a portion of the seam region of the belt after a treatmentstrip has been applied. Depending on the configuration of the lamp, theoptics can form a heat spot on a portion of the strip and the seamregion, as well as an actuator that adjusts the optics so that the heatspot traverses a width of the seam region and/or another actuator thatmoves the pressure wheel with the heat spot to compress a portion of thestrip and the seam region that the heat spot has heated; or, where thelamp extends across substantially the entire seam region, the optics canform a heat line across the entire seam region. The belt hold system cancomprise a vacuum system including at least one opening in the outersurface of the tube, a sealed end of the tube, and an unsealed end ofthe tube in selective fluid communication with a vacuum source.Alternatively, the belt hold system can include a bar that extendsthrough a portion of the belt farthest from the tube and selectivelypulls the belt against the tube; the bar can be connected to an actuatorthat selectively exerts force on the belt to pull the belt against thetube, or can be placed in the belt by an operator and pulls the beltthrough the action of gravity on the bar.

Although this invention deals with the seam overcoat materialformulations, it also relates to apparatus and lamination process foreffective flexible electrostatographic imaging member belts seamovercoating application, the following will focus only on seamedflexible electrophotographic imaging member belts to simplifydiscussion.

A more complete understanding of the process and apparatus of thepresent invention can be obtained by reference to the accompanyingdrawings wherein:

BRIEF DESCRIPTION OF DRAWINGS

In the detailed description, reference is made to the accompanyingdrawings, in which: FIG. 1 illustrates a schematic partialcross-sectional view of a multiple layered flexible sheet ofelectrophotographic imaging member material with opposite endsoverlapped.

FIG. 2 shows a schematic partial cross-sectional view of a multiplelayered seamed flexible electrophotographic imaging member belt derivedfrom the sheet illustrated in FIG. 1 after ultrasonic seam welding.

FIG. 3 illustrates a schematic partial cross-sectional view of amultiple layered seamed flexible electrophotographic imaging member beltwhich has mechanical failure due to fatigue induced seamcracking/delamination problem.

FIG. 4 shows the cross sectional side view of a strip laminatorconsisting of a thin thermoplastic polymer laminate lightly adheringover a flexible carrier backing substrate layer readily for use ininvention seam overcoating application.

FIG. 5 is a schematic sectional side view of a seamed flexibleelectrophotographic imaging member belt in which the seam is held downonto the flat supporting surface of an elongated support member, with astrip laminator (not shown) positioned directly over the seam, whilesubjected to an elevated temperature seam overcoating/laminationprocess, utilizing a flat surfaced narrow heating and compression bar.

FIG. 6 shows an isometric, schematic view of a seamed flexibleelectrophotographic imaging member belt in which the seam is parked on,with a strip laminator placed directly over the seam, and held on a flatsurface of an elongated support member while subjected to an alternativeseam overcoating/lamination process, utilizing a hot rolling compressionwheel.

FIG. 7 is an isometric schematic view of a seamed flexibleelectrophotographic imaging member belt in which the seam is parked onand held against the arcuate convex surface of an elongated supportmember by vacuum, while heating with a focus infrared red spot andcoupled with a compression rolling wheel, is subjected to the heatingand compression processing of the present invention to yield seamovercoating/lamination and stress-release results.

FIG. 8 illustrates the schematic, sectional side view of the seamovercoating/lamination processing arrangement of FIG. 7, but with theonly exception that this exemplary embodiment used instead a CO₂ laserheat radiation source to replace the IR heating source shown in FIG. 7for achieving the very same invention result.

FIG. 9 shows the isometric, schematic view of a seamed flexibleelectrophotographic imaging member belt in which the seam is parked onand held over the arcuate convex surface of an elongated support memberby vacuum while subjected to another invention variance seamovercoating/lamination processing, utilizing a hot rolling compressionwheel. In the drawings and the following below, it is to be understoodthat like numeric designations refer to components of like function.

DETAILED DESCRIPTION

Although specific terms are used in the following description for thesake of clarity, these terms are intended to refer only to the exemplaryembodiment selected for illustration in the drawings, and are notintended to define or limit the scope of invention.

Referring to FIG. 1, there is illustrated a flexible electrophotographicimaging member 10 in the form of a belt formed from a sheet having afirst end marginal region 12 overlapping a second end marginal region 14to form an overlap region ready for a seam forming operation. Theflexible electrophotographic member 10 can be used within anelectrophotographic imaging device and can be a single film substratemember or a member having a film substrate layer combined with one ormore additional coating layers. At least one of the coating layerscomprises a film forming binder.

The flexible electrophotographic imaging member 10 can be a single layeror comprise multiple layers. If the flexible electrophotographic imagingmember 10 is to be a negatively charged photoreceptor device, theflexible electrophotographic imaging member 10 may comprise a chargegenerator layer sandwiched between a conductive surface and a chargetransport layer. Alternatively, if the flexible imaging member 10 is tobe a positively charged photoreceptor device, the flexible imagingmember 10 may comprise a charge transport layer sandwiched between aconductive surface and a charge generator layer.

The layers of the flexible electrophotographic imaging member 10 cancomprise numerous suitable materials having suitable mechanicalproperties. Examples of typical layers are described in U.S. Pat. Nos.4,786,570, 4,937,117, and 5,021,309, the entire disclosures of which areincorporated herein by reference. The flexible electrophotographicimaging member 10 of embodiments shown in FIG. 1 comprises, from top tobottom, a charge transport layer 16, a generator layer 1, an interfacelayer 20, a blocking layer 22, a conductive ground plane layer 24, asupporting layer 26, and an anti-curl back coating layer 28. It shouldbe understood that the thicknesses of the layers are conventional andthat a wide range of thicknesses can be used for each of the layers.

The end marginal regions 12 and 14 can be joined by any suitable meansincluding gluing, taping, stapling, pressure and heat fusing to form acontinuous member such as a belt, sleeve, or cylinder. However, for easeof belt fabrication, short operation cycle time, and the mechanicalstrength of the fabricated joint, embodiments employ an ultrasonicwelding process to join the end marginal regions 12 and 14 into a seam30 in the overlap region, as shown in FIG. 2, to form a seamed flexibleelectrophotographic imaging member 10 in the form of a belt. In theultrasonic seam welding process, ultrasonic energy applied to theoverlap region is used to melt suitable layers such as the chargetransport layer 16, generator layer 18, interface layer 20, blockinglayer 22, part of the support layer 26 and/or anti-curl back coatinglayer 28. Direct fusing of the support layer achieves optimum seamstrength.

Upon completion of welding the overlap region of the flexibleelectrophotographic imaging member sheet into a seam 30 using ultrasonicseam welding technique, the overlap region is transformed into anoverlapping and abutting region as illustrated in FIGS. 2 and 3. Withinthe overlapping and abutting region, the portions of the flexibleelectrophotographic imaging member 10, which once formed the endmarginal regions 12 and 14, are joined by the seam 30 such that the onceend marginal regions 12 and 14 are overlapping and abutting one another.The seam 30, indicated by a dashed line in FIG. 2, comprises twovertical portions joined by a horizontal portion. The midpoint of seam30 can be represented by an imaginary centerline extending the length ofseam 30 from one edge of belt 10 to the opposite edge, the imaginarycenterline (not shown) running along the middle of the horizontalportion which joins the two vertical portions illustrated in FIG. 2. Inother words, a plan view (not shown) of the horizontal portion of seam30 would show a strip much like a two lane highway in which thecenterline would be represented by the white divider line separating thetwo lanes, the two lanes comprising end marginal regions 12 and 14. Theflexible electrophotographic imaging member 10 has a first majorexterior surface or side 32 and a second major exterior surface or side34 on the opposite side. The seam 30 joins the flexibleelectrophotographic imaging member 10 so that, the bottom surface 34 atand/or near the first end marginal region 12 is integral with the topsurface 32 at and/or near the second end marginal region 14. Generally,the bottom surface 34 includes at least one layer immediately above thebottom of the belt in the first end marginal region 12, and the topsurface 32 includes including at east one layer immediately below thetop of the belt in the second end marginal region 14.

The welded seam 30 in embodiments also contains upper and lowersplashings 68 and 70 at each end thereof as illustrated in FIGS. 2 and4. The splashings 68 and 70 are formed in the process of joining the endmarginal regions 12 and 14 together when molten material is necessarilyejected from either side of the overlap region to facilitate directsupport-layer-to-support-layer fusing. The upper splashing 68 is formedand positioned above the overlapping end marginal region 14, abuttingthe top surface 32 and adjacent to and abutting the overlapping endmarginal region 12. The lower splashing 70 is formed and positionedbelow the overlapping end marginal region 12, abutting bottom surface 34and adjacent to and abutting the overlapping end marginal region 14. Thesplashings 68 and 70 extend beyond the sides and the edges of the seam30 in the overlap region of the welded flexible electrophotographicimaging member 10. The extension of the splashings 68 and 70 beyond thesides and the edges of the seam 30 is undesirable for many machines suchas electrophotographic copiers, duplicators, and other such machinesthat require precise edge positioning of a flexible electrophotographicimaging member 10 during machine operation. Generally, the extension ofthe splashings 68 and 70 at the belt edges of the flexibleelectrophotographic imaging member 10 are removed by a notchingoperation.

A typical upper splashing 68 has a height or thickness t of about 90micrometers and projects about 17 microns above the surface of theoverlapping end marginal region 12. Each of the splashings 68 and 70 hasan uneven, but generally rectangular, shape including one side 72, afree side that forms a free end, extending inwardly toward top surface32 from an outwardly facing side 74, which extends substantiallyparallel to either the top surface 32 or the bottom surface 34. The freeside 72 of the splashing 68 forms an approximately perpendicular angleθ₁ with the bottom surface 34 of the flexible electrophotographicimaging member 10 at a junction 76. Likewise, the free side 72 of thesplashing 70 forms an approximately perpendicular angle θ₂ at a junction78 of the free side 72 of the lower splashing 70 and the bottom surface34 of the flexible imaging member 10. Both junctions 76 and 78 createfocal points for stress concentration and become initial points offailure affecting the mechanical integrity of the flexibleelectrophotographic imaging member 10.

During machine operation, the seamed flexible electrophotographicimaging member 10 cycles or bends over rollers, particularly smalldiameter rollers, of a belt support module within an electrophotographicimaging apparatus. As a result of dynamic bending/flexing of theflexible electrophotographic imaging member 10 during cycling, therollers repeatedly exert a force on the flexible imaging member 10 thatcauses large stresses to develop generally adjacent to the seam 30 dueto the excessive thickness and material discontinuity thereof. Thestress concentrations that are induced by bending near the junctionpoints 76 and 78 can reach values much larger than the average value ofthe stress over the entire length of the flexible electrophotographicimaging member 10. The induced bending stress is inversely related tothe diameters of a roller that the flexible imaging member 10 bends overand directly related to the thickness of the seam 30 of the flexibleelectrophotographic imaging member belt 10. When a structural member,such as the flexible electrophotographic imaging member 10, contains asudden increase in cross-sectional thickness at the overlap region, highlocalized stress occurs near the discontinuity, e.g. junction points 76and 78.

When the flexible electrophotographic imaging member 10 bends over therollers of a belt module within an electrophotographic imagingapparatus, the bottom surface 34 of the flexible electrophotographicimaging member 10, which is adapted to contact the exterior surface ofthe roller, is compressed. In contrast, the top surface 32 is stretchedunder tension. This is attributable to the fact that the top surface 32and bottom surface 34 move in a circular path about the circular roller.Since the top surface 32 is at greater radial distance from the centerof the circular roller than the bottom surface 34, the top surface 32must travel a greater distance than the bottom surface 34 in the sametime period. Therefore, the top surface 32 must be stretched undertension relative to a generally central portion of the flexibleelectrophotographic imaging member 10 (the portion of the flexibleelectrophotographic imaging member 10 generally extending along thecenter of gravity of the flexible imaging member 10). Likewise, thebottom surface 34 must be compressed relative to the generally centralportion of the flexible imaging member 10 (the portion of the flexibleelectrophotographic imaging member 10 generally extending along thecenter of gravity of the flexible electrophotographic imaging member10). Consequently, the bending stress at the junction point 76 will betension stress, and the bending stress at the junction point 78 will becompression stress.

Compression stresses, such as at the junction point 78, rarely causeseam 30 failure. Tension stresses, such as at junction point 76,however, are much more of a problem. The tension stress concentration atthe junction point 76 in great likelihood will eventually result incrack initiation through the electrically active layers of the flexibleelectrophotographic imaging member 10 as illustrated in FIG. 3. Theillustrated crack 80 is adjacent to the top splashing 68 of the secondend marginal region 14 of the flexible electrophotographic imagingmember 10. The generally vertically extending crack 80 initiated in thecharge transport layer 16 continues to propagate through the generatorlayer 18. Inevitably, the crack 80 extends generally horizontally todevelop seam delamination 81 which is propagated through the relativelyweak adhesion bond between the adjoining surfaces of the generator layer18 and the interface layer 20.

The formation of the local seam delamination 81 is typically called seampuffing. The excess thickness of the splashing 68 and stressconcentration at the junction 76 causes the flexible electrophotographicimaging member 10 to perform, during extended machine operation, asthough a material defect existed therein. Thus, the splashing 68 tendsto promote the development of dynamic fatigue failure of the seam 30 andcan lead to separation of the joined end marginal regions 12 and 14severing the flexible imaging member 10. Consequently, the service lifeof the flexible imaging member 10 is shortened.

In addition to seam failure, the crack 80 acts as a depository site andcollects toner, paper fibers, dirt, debris, and other unwanted materialsduring electrophotographic imaging and cleaning of the flexibleelectrophotographic imaging member 10. For example, during the cleaningprocess, a cleaning instrument, such as a cleaning blade, willrepeatedly pass over the crack 80. As the site of the crack 80 becomesfilled with debris, the cleaning instrument dislodges at least someportion of this highly concentrated level of debris from the crack 80.The amount of the debris, however, is beyond the removal capacity of thecleaning instrument, and portions of the highly concentrated debris aredeposited onto the surface of the flexible electrophotographic imagingmember 10. In effect, the cleaning instrument spreads the debris acrossthe surface of the flexible electrophotographic imaging member 10instead of removing the debris therefrom.

In addition to seam failure and debris spreading, the portion of theflexible member 10 above the seam delamination 81, in effect, becomes aflap which moves upwardly. The upward movement of the flap presents anadditional problem during the cleaning operation. The flap becomes anobstacle in the path of the cleaning instrument as the instrumenttravels across the surface of the flexible electrophotographic imagingmember 10. The cleaning instrument eventually strikes the flap when theflap extends upwardly. As the cleaning instrument strikes the flap,great force is exerted on the cleaning instrument which can lead todamage thereof, e.g., excessive wear and tearing of the cleaning blade.

In addition to damaging the cleaning blade, the striking of the flap bythe cleaning instrument causes unwanted vibration in the flexibleelectrophotographic imaging member 10. This unwanted vibration adverselyaffects the copy/print quality produced by the flexibleelectrophotographic imaging member 10. The copy/print is affectedbecause imaging occurs on one part of the flexible imaging member 10simultaneously with the cleaning of another part of the flexible imagingmember 10.

To overcome the problems associated with seam cracking and delamination,embodiments employ a seam treatment article, treatment strip, orlaminator strip 32 applied in a strip to the seam region in a particularfashion. A laminator strip 32 according to embodiments, shown, forexample, in cross-section in FIG. 4, comprises a film or thin laminate34 adhering to a flexible backing substrate layer 36. Embodiments employa thickness of the laminate 34 of between about 5 micrometers and about50 micrometers; particularly, good results can be achieved with athickness of between about 10 micrometers and about 30 micrometers.

Laminate 34 is a film-forming thermoplastic polymer that, inembodiments, is substantially identical or substantially compatible with(compatible means it can form polymer blend) the polymer binder of thecharge transport layer of the flexible imaging member. In this context,compatible means that the thermoplastic polymer film 34 can form apolymer blend with the polymer binder of the charge transport layer.Alternatively, embodiments can employ a laminate 34 that is a polymerblend of the polymer binder and a film-forming thermoplastic polymer. Inaddition, the laminate 34 of embodiments can contain organic chargetransport molecule of the same kind or of a different kind as that ofthe charge transport layer. The laminate 34 of embodiments can have awidth of from about 2 mm to about 15 mm, but can yield better resultswith a width of between about 3 and about 10 mm. The laminate 34 must becompressible and malleable under the heat and compression processingconditions to enable bonding to the seam and facilitate filling thephysical discontinuities of the seam.

Although the flexible backing substrate layer 36 can be a metallic foilor a high glass transition temperature (T_(g)) flexible polymersubstrate, use of a polymer substrate that is substantially not affectedby the heat and compression of embodiments is preferred. Materials suchas polyethylene terephthalate (PET, also known as Mylar), polyethylenenaphthalate (Kadelex), polyimide (Kapton), and the like meet suchrequirements and can be used in embodiments. A thickness of betweenabout 2 mils and about 5 mils is satisfactory in embodiments, and awidth equal to the width of the laminate can be employed, with evenbetter seam overcoating/lamination results achieved in embodimentshaving a substrate about 2 to about 5 mm wider on each side of thelaminate 34. The laminate 34 preferably has, in embodiments, an 180°adhesion peel strength over the backing substrate layer 36 of betweenabout 3 g/cm and about 8 g/cm to ensure that the substrate can bereadily stripped off of the overcoat after completion of the treatmentprocess. Although in embodiments the laminator strip 32 is preferred tobe a dual-layer strip as illustrated in FIG. 4, it can also be just asingle laminate layer 34 if desired.

An apparatus for carrying out embodiments of the treatment methodincludes a heat source or heating means that heats the seam region (thearea of the imaging member 10 around the seam 30) after the laminate hasbeen placed in contact with the seam. Embodiments also include means forapplying pressure to the heated region. In embodiments, as shown in FIG.5, a hot compression bar or plate 145 is the heat source and provideslocalized heating and compression of the region about the seam 30,directly over which a laminator strip (not shown) has been placed, toyield seam overcoating/lamination result. Embodiments also include meansto hold the seam region in place during treatment, such as a vacuumsystem. Thus, while the seam 30 of imaging member 10 is positioned andvacuum held down on the flat smooth supporting surface of support member138, the heat source heats the seam region and strip. The hotcompression bar 145, preferably metallic, has a smooth outer contactingsurface that is coated with a thin abhesive or low surface energycoating to prevent imaging layer material and the laminator strip fromadhering to its surface when seam overcoating/lamination processing iscarried out. Any suitable abhesive or low surface energy material can beemployed, including fluoropolymers, such as Teflon, silicone, polyimide,and the like. A thin Teflon coating on the smooth contacting surface ispreferred in embodiments because it promotes ease of release andprevents imaging member material from sticking to the surface of theheating/compression bar 145 when making compression contact during seamlamination processing treatment. The efficiency of heat energy deliveryfrom the heating/compression bar 145, preferably comprising resistanceelements (not shown) temperature control, to the laminator strip andseam area during contact is adjusted by any suitable device, such as aconventional adjustable variac 132, to provide sufficient power to raisethe temperature of the laminator strip and seam area from about 20° C.to 70° C. above the T_(g) of the thermoplastic polymer material in thecharge transport layer (T_(g) of the laminate if it is lower than thatof the charge transport layer) of the electrophotographic imaging member10. This thermoplastic polymer material is the top layer of the imagingmember, which is for example the charge transport layer comprising apolymer binder with dissolved or molecularly dispersed charge transportcompound, of electrophotographic imaging member. Conventionalthermostats can be employed to regulate the temperature of theheating/compression bar 145A narrow vacuum channel 140 can be used inembodiments on each side of the support member to vacuum hold the belt10 down against the flat supporting surface of support member 138. Thevacuum channels 140 can be about 25 millimeters apart and extend, oneach side of seam 30, along the support member 138 to about the fullwidth of the belt 10. Suitable widths for the vacuum channels can beabout 60 mils (1.5 mm). The upper ends of the vacuum channels 140 areopen, and the lower ends are connected by a suitable device, such as avalved flexible hose (not shown), leading to any suitable vacuum source.After belt 10 is placed onto support member 138, such as manually or byany suitable conventional robotic device, the initially closed valve onthe flexible hose to the vacuum source is opened, enabling the device tosuck the belt 10 against the upper, flat, smooth surface of supportmember 138. This suction holds the belt 10 substantially immobile onsupport member 138 during seam overcoating/lamination processing. Ifdesired, embodiments can include a plurality of holes of any suitableshape (e.g. round, oval, square, and the like) instead of or in additionto the channels 140. The number and size of the holes should besufficient to hold the belt 10 against the support member. The size ofthe channels and holes should be small enough to avoid distortion of thebelt during the seam area heating and compression process. Theresistance of the belt to distortion when suction is applied depends onthe beam strength of the specific belt employed, which in turn dependsupon the specific materials in and thickness of the layers in the belt10. The support member 138 may comprise any suitable hard material.Typical materials include, for example, hard plastic, having a smoothand polished surface. Preferably, support member 138 is metallic.

In embodiments, the heating/compression bar 145 preferably has a widthof between about 6 millimeters and about 30 millimeters with a lengthsufficient to cover the seam 30 along the entire width of the imagingmember 10. In the process, heating/compression bar 145 compressesagainst laminator strip and seam 30 to make intimate force contact withthe seam. Such intimate force contact made by heating/compression bar145 substantially instantaneously elevates the temperature of a smalllocalized region of the imaging layer adjacent to seam 30 of the imagingmember containing thermoplastic polymer. This small localized region ofthe imaging layer in the upper portion of the seam region is heatedsubstantially instantly above the T_(g) of the thermoplastic polymer.Typically, the T_(g) of a film forming polymer used for anelectrophotographic imaging layer, e.g., the charge transport layer, isat least about 45° C. to satisfy most imaging belt machine operatingconditions. The imaging layer of an imaging member is a charge transportlayer if the imaging member is an electrophotographic imaging member anda dielectric layer if the imaging member is an electrographic imagingmember. Since the charge transport layer of embodiments is a compositecomprising a polymer binder, a dissolved or molecularly dispersed chargetransport organic compound, and optional pigment particles, the T_(g) inthis case is a T_(g) of the combination. Thus, the expression polymermaterial as employed herein is defined as the polymer and any othermaterial present in an imaging layer or in the laminate. Such polymermaterials used for electrophotographic imaging layer coatingapplications normally have a T_(g) of at least about 45° C. to satisfymost imaging belt machine operating conditions. Preferably, the seamarea heating and compression process is carried out between about 20° C.and about 70° C. above the T_(g) of the thermoplastic polymer materialof the imaging layer (e.g., charge transport layer) or the laminate(whichever one has the lower T_(g)) in order to yield strong overcoatedlaminate adhesion bonding onto the seam region, surface smoothingresult, good physical continuity transition at the seam region, and seamregion thickness reduction outcome. Occurrence of material melting,distortion, or cutting through of the seam components duringheat/compression processing treatment should be avoided, because thisweakens or damages the belt.

For processing a flexible imaging member having a skewed seam, the beltitself can be cocked and adjusted such that the seam is positioned,without skewing, on the flat support member 138 and under theheating/compression bar 145. Compression bar 145 contacts and compressesthe laminator strip and seam 30 while the belt 10 is held down againstthe flat supporting surface of the support member 138 by the vacuumchannels 140. During pressure contact, the heat conduction from the hotcompression bar 145 heats up the seam region to the desirabletemperature and the compression pressure generated by the barfacilitates the bonding of the laminate to the seam to provide surfacesmoothing, eliminate or minimize seam region physical discontinuity, aswell as reduce seam region thickness. The compression bar 145 preferablyexerts a compressive pressure of between about 70 lbs/in² (5 kg/cm²) andabout 770 lbs/in² (55 kg/cm²) on the laminator strip and seam region inorder to achieve the invention seam overcoating/lamination result. Aneffective temperature range used for heat treating/laminating anovercoat onto the seam of a typical flexible photoreceptor belt,comprising a top exposed charge transport layer containing athermoplastic polycarbonate polymer and a dissolved or molecularlydispersed charge transport compound, is appropriately selected to be ina range of between about 85° C. (185° F.) and about 97° C. (206° F.),based on the fact that the charge transport layer with a thickness ofabout 24 micrometers has a T_(g) of about 82° C. (180° F.). Since thepreferred imaging member seam lamination treatment embodiment of thisinvention involves heat and pressure contact with only the seam region(a small surface area), the desired lamination treatment temperature isreadily reached and cooling of the heat treated seam region to roomambient is quickly attained, the entire overcoating/laminationprocessing is completed within a short cycle time. Generally, the cycletime of the seam overcoating/lamination processing for the typicalphotoreceptor belt can be accomplished in less than about 20 secondswith the process of this invention for belts having a width of betweenabout 20 centimeters and about 60 centimeters.

An alternate heat source and pressure applying system usable inembodiments is illustrated in FIG. 6. A single heated, rotatablecompression wheel 150 is rolled over the laminator strip 32 and seam 30of belt 10, which is parked and held down by vacuum (not shown) on asmooth flat surface of support member 148. The geometry and design offlat support member 148 is identical to the support member 138 shown inFIG. 5. Compression wheel 150 can have a flat outer peripheral surfaceprofile that exerts straight line compression contact against the seamto smooth the exposed surface of seam 30, eliminate protrusions, andreduce the seam region thickness. The direction of the compression forcevector is perpendicular to the surface of the support member. The loweredge profile of the peripheral surface of wheel 150 is straight andsubstantially parallel to the smooth flat surface of the support member148 during seam treatment. This peripheral surface should be maintainedat a temperature sufficient to raise the temperature of thethermoplastic polymer material of the top layer, the imaging layer, ofthe belt seam to at least its glass transition temperature T_(g). Theperipheral surface of wheel 150 preferably has a thin coating surface ofabhesive material to prevent imaging layer material from adhering to theperipheral surface of wheel 150 during the seam overcoating/laminationprocess. Any suitable abhesive material can be used. Typical low surfaceenergy or abhesive materials include, for example, fluoropolymers, suchas Teflon, silicone, polyimide, and the like. The heated compressionwheel 150 is preferably metallic with a smooth peripheral surface.Heating of the wheel can be accomplished by any suitable device such as,for example, by an electromagnetic induction RF heating mechanism 152 togive the desired temperature when wheel 150 traverses the full width ofbelt 10 and over seam 30 to compress the seam. Alternatively, any othersuitable device, such as a resistance wire heating system 154 can beemployed to heat compression wheel 150. Where the resistance wire ispart of the wheel, any suitable electrical connection, such as sliprings 156, can be used to provide electrical energy to the resistancewires. Sufficient heat energy should be supplied to wheel 150 toadequately heat the peripheral surface thereof. Preferably, the hotrotatable compression wheel 150 is reciprocated and the support member148 carrying belt 10 remain stationary during the seam treatment.However, if desired, the support tube and belt can be moved and thewheel remains stationary or both can be reciprocated to achieve relativemotion with each other. Wheel 150 remains rotatable and exerts a linearcompression force of between about 1 lb/in. (0.18 kilograms/cm) andabout 20 lbs/in. (3.6 kilograms/cm) over the laminator strip and seamregion during any of the aforesaid seam treatment embodiments. Since theline force of compressive contact, generated by the continuous rollingwheel pressure action against the laminator strip 32 across the entirebelt width, at least matches or is greater than the width of strip 32 atthe site on the seam heated by the hot wheel 150, the compressive lineof force contact is perpendicular to the seam length and of infinitenumbers or continuum as the hot wheel rolls and traverses to effect fullseam overcoating/lamination.

Another heat source usable in embodiments includes infrared radiationsources. Embodiments can, for example, use incandescent lamps or highintensity discharge lamps as the heat source. Additionally, optics, suchas, for example, reflectors, lenses, and filters, can be used to alterthe character, path, and intensity of the output of such infraredradiation sources. An example of an infrared radiation heat sourcearrangement usable in embodiments is illustrated in FIG. 7. A high powertungsten halogen quartz bulb infrared (IR) is the heat source 103, andprovides localized, focused IR heating. Preferably, optics are employedto create a small, substantially circular heat spot that preferablystraddles the laminator strip 32 after the strip 32 is placed on theseam 30 of imaging member 10. The seam region is, for example, held downon a hollow support cylinder 90 at about the 12 o″clock position. A freerotating compression wheel 108 follows the heat spot to providelocalized compression to the heated portions of the laminator strip 32and the seam region of imaging member 10. The circular IR heat spotshould have a diameter sufficient to cover, yet not to exceed, theentire width of the laminator strip 32 in order to impart an effectiveresult. In embodiments, this width can be between about 2 mm and about15 mm in spot diameter. Compression wheel 108, trailing right behind theIR heat spot, is biased against the laminator strip 32 (placed over theseam 30) by a spring 110 to provide the needed compression force. Boththe IR heat source 103 and compression wheel 108 are supported by anysuitable means 112 (partially shown), such as part of the frame of theprocessing device. An advantage of using a curved, convex surface is toprovide seam bending stress release; the processed seam obtainedaccording to embodiments employing such a curved surface can yield anenhanced seam cracking/delamination life extension result under normaloperating conditions.

As in the previous examples, a narrow vacuum channel 104 can be used inembodiments on each side of the hollow support cylinder 90 to hold thebelt 10 down against the arcuate convex surface of cylinder 90. Thevacuum channels 140 can be about 180° apart and extend axially alongeach side of cylinder 90. Suitable widths for the vacuum channels can beabout 60 mils (1.5 mm). One end of tube 90 is sealed (not shown) and theother is connected by a suitable device such as a valved flexible hose(not shown) to any suitable vacuum source. After belt 10 is placed ontothe tube 90, such as manually or by any suitable conventional roboticdevice, the initially closed valve on the flexible hose to the vacuumsource is opened, enabling the device to suck the belt 10 against theupper, arcuate, convex surface of tube 90 and to achieve a substantially180 degree wrapping of belt 10 around the upper, arcuate, convex surfaceof tube 90. plugs, seals, end-caps, or the like can be used to close theend openings of supporting tube 90 to ensure vacuum buildup. Thissuction holds the belt 10 substantially immobile on the tube 90 duringseam overcoating/lamination processing. If desired, embodiments caninclude a plurality of holes of any suitable shape (e.g. round, oval,square, and the like) instead of or in addition to the slots 104. Thenumber and size of the holes should be sufficient to hold the belt 10against the support member. The size of the slots and holes should besmall enough to avoid distortion of the belt during the seam areaheating and compression process. The resistance of the belt todistortion when suction is applied depends on the beam strength of thespecific belt employed, which in turn depends upon the specificmaterials in and thickness of the layers in the belt 10.

In embodiments, the supporting cylindrical tube 90 for imaging belt 10has an outer radius of curvature of, for example, between about 9.5millimeters and about 50 millimeters (i.e. diameter of curvature ofbetween about 19 millimeters and about 100 millimeters). When the radiusof curvature chosen for invention seam overcoating/lamination processingis less than about 9.5 millimeters (i.e. diameter of curvature of about19 millimeters), the beam rigidity of the electrophotographic imagingbelt will raise the belt 10 bending resistance so high that only a verysmall curvature can be achieved prior to carrying out the treatment.When the radius of curvature is greater than about 50 millimeters (i.e.diameter of curvature of about 100 micrometers), the seam stress-releaseis not fully realized because little or insignificant seam bendingstress-release in the imaging layer is obtained.

With reference again to FIG. 7, the electrophotographic imaging belt 10is positioned with belt seam 30 parked directly over supportingcylindrical tube 90, so that the arcuate convex surface of tube 90 is inintimate contact with the back surface of belt 10 with the top imagingsurface of belt 10 facing away from tube 90. If desired, to furtherassure intimate contact and conformance of the belt to the top convexsurface of the tube 90 (say for instance, the belt is making an 180°wrap around the tube), a slight belt tension can be applied to the belt10 by any suitable means such as, for example, by inserting a lightweight cylindrical tube of the same outer diameter as tube 90 inside thelower loop of belt 10 while the belt 10 is hanging from tube 90. Tube 90can be cantilevered by securing one end to a supporting wall or frame. Adesirable imaging member wrapped angle for the seam segment parking overthe back supporting cylindrical tube 90 should provide an arcuate convexarea at the seam region at least about as wide as the diameter of theheated substantially circular IR spot. It is preferred that the wrapangle encompassing the seam and region of the belt adjacent each side ofthe seam conforming to the arcuate convex supporting surface of thesupport member be between about 10° and about 180°. The material usedfor tube 90 must be very hard and nearly incompressible. It can be ofany suitable material, including, for example, metal, plastic,composites, and the like, but is preferably metallic. Although theimaging member 10 is shown to be held down against the convex uppersurface of the full circular support tube 90 in FIG. 7, the elongatedsupport member may alternatively have any other suitable shape such asan elongated half circle, an elongated partial circle, a bar having anarcuate convex surface on the side contacting the seam, and the like,provided the support member employed has an arcuate convex curve surfacesufficient to retain and hold down the entire length of the seam regionof the parked belt during seam overcoating/lamination processing.

The IR tungsten halogen quartz bulb 105 emits a dominant radiantwavelength of about 0.98 micrometer. Preferably, at least about 80percent of the radiation emitted by the tungsten halogen quartz bulb 105has a radiant wavelength of about 0.98 micrometer. A typical,commercially available, high powered IR tungsten halogen quartz bulb 105that can be used in heating source 103 is a Model 4085 infrared heatingbulb, available from Research, Inc., and comprises a 750 watt tungstenhalogen quartz bulb (750Q/CL, available from Research, Inc.) positionedat a focal point inside an aluminum hemiellipsoid shaped heat reflector106 similar to the schematic arrangement shown in FIG. 7. This IRheating bulb 105 has an adjustable energy output to give suitable IRheat spot temperature; for example, with heat flux densities to 650watts per square inch (1007 kilowatts per square meter) at a 6millimeter diameter focal point of the converging infrared energy. A 500watt tungsten halogen quartz bulb is also available form Research, Inc.,and other suitable bulbs could be obtained from other manufacturers.Bulb 105 is positioned inside an hemiellipsoid reflector 106 at thefocal point of the reflector so that all the reflected energy from bulb105 converges at another focal point outside of the reflector 106. Ifthe hemiellipsoid reflector were formed into a complete ellipsoid ratherthan half an ellipsoid, there would be two symmetrically positionedfocal points, one where the bulb 105 is located and the other where thereflected energy from the bulb 105 converges. The reflector can be madeof any suitable coated or uncoated material. Typical materials include,for example, uncoated aluminum, gold plated metal, stainless steel,silver, and the like. If desired, the reflector can contain openings tofacilitate the circulation of a cooling gas. An increase in the area ofthe openings in the reflector will reduce the amount of reflected energyfrom bulb 105 that converges at another focal point outside of thereflector 106. The distance between the reflector and the outer surfaceof the seam is adjusted by any suitable positioning device, such as, forexample, a conventional lead screw and ball device 88. Any othersuitable device, such as a rod fixed to a movable carriage and slidingcollar fitted with a set screw, the collar being secured to thereflector and slidable on the rod, can be used so long as a highintensity, substantially circular IR spot can be formed. The diameter ofthe spot is, for example, between about 2 millimeters and about 15millimeters and covers the entire width of the laminator strip 32, thishigh intensity focused circular IR spot substantially instantaneouslyelevates the temperature of only a small localized region, sufficientenough to cover the width of the laminator strip 32 and to exceed theglass transition temperature (T_(g)) of the charge transport layer inthe seam area or the laminate 34 of laminator strip 32. Typically, theT_(g) of a film forming polymer in the formulation used forelectrophotographic imaging layer coating applications is at least about45° C. to satisfy most imaging belt machine operating conditions.Preferably, the heat exposure spot in embodiments should be betweenabout the 20° C. and about 70° C. above the lower of the T_(g) of theimaging layer or the laminate 32 to achieve sufficient seamovercoating/lamination and stress release results.

the IR heating source 103 is moved substantially continuously orincrementally, along and above, the laminator strip 32 and the seam 30,by manually or automatically means, such as by any suitable horizontallyreciprocateable carriage system (not shown). Typical horizontallyreciprocateable carriage systems include, for example, ball screw, twoway acting air cylinder, lead screw and motor combination, belt or chaindrive slide system, and the like. A relative speed of movement betweenthe heating source/compression wheel assembly and the support tube 90holding the seamed belt 10 can be from about 1 centimeter to about 20centimeters per second with satisfactory results. A relative speedbetween about 2.5 centimeters and about 12.5 centimeters per secondyields better results. Alternatively, if desired, the whole integralpart of the IR heat source 103 with compression wheel assembly can beheld stationary while the tube 90 carrying the hold-down imaging membercan be set to motion, in exact but reversed manners as just described,to achieve the same processing outcome.

The rotatable compression wheel 108 illustrated in FIG. 7 can have aperipheral surface with an arcuate, concave cross section with acurvature that substantially corresponds to or is slightly larger thanthe predetermined curvature of the arcuate, convex, substantiallysemicircular cross section of the elongated surface of the upper half ofthe support tube 90. The wheel 108 produces a compression line pressurecontact between the peripheral surface of the wheel and outer surface ofthe seam, augmented by tension force generated by spring 110. To produceeffective invention seam area overcoating/lamination result that canyield good seam region physical continuity and an improved surfacemorphological profile, it is important that the peripheral surface ofthe compression wheel has an arcuate concave radius of curvature.Preferably, the arcuate concave radius of curvature is between about 9.5millimeters and about 55 millimeters. The arcuate concave radius ofcurvature should correspond to or be slightly larger (e.g., by up toabout 10 percent larger) than the convex surface radius of curvature ofthe support tube 90, which preferably has a convex radius of curvatureof between about 9.5 millimeters and about 50 millimeters. The radius ofthe compression wheel 108, measured from its center of rotation or axisto the midpoint of line contact against the seam, can be, for example,between about ⅛ inch (3.2 millimeters) and about ½ inch (12.7millimeters), so long as the pressure application requirements ofembodiments are met. Measurement of the radius of the compression wheel108 is analogous to measuring the radius at the waist of an hour glass,the compression wheel 108 having a cross sectional shape (taken alongthe axis of the hour glass) similar to that of an hour glass.

Since the heated localized site cools very quickly, a very smallcompression wheel radius measured at the waist allows delivery of thecircular hot spot from the IR heat source 103 to the laminator strip(placed over the seam) closer to the imaginary axis of the wheel or theline of compression so that it is in tangential contact with waist ofthe wheel (e.g., bottom of the arcuate channel at about the 3 o″clockposition of the wheel when a vertically aligned compression wheel isemployed). Preferably, contact of the IR heat spot to the waist or anyother part of the wheel 108 is avoided to prevent heat build up in thewheel. By positioning the focus beam of the IR close to the waist of asmall radius wheel, the localized site heated by the IR heat spot isvery close to the line of compressive contact exerted by the compressionwheel against the laminator strip 32 from one side of the seam region tothe other which, therefore, allows quick compression force applicationby the wheel to the localized heated spot before this hot spot cools toa temperature below the T_(g) of heated polymer material in thelocalized site and thereby effecting seam overcoating/lamination result.However, the radius at the waist of the wheel should not be so smallthat rigidity of the compression wheel is compromised. Thus, forexample, the waist radius of the compression wheel should not be sosmall as to cause the wheel or wheel support member to bend when it isused to apply a compression force to the seam region. The limiting waistradius of the wheel 108 is strongly dependent on the specific materialsused to make the wheel. Similarly, bending resistance is also dependenton the specific materials selected for the wheel.

If desired, embodiments of the IR heat source 103 can be designed tohave varying adjustable positions such that it can be tilted, inclined,or angled to allow positioning of the incident focused IR heat spot evencloser to the line of compressive contact between the compression wheel108 and the laminator strip/seam region. Since the line of compressivecontact generated by the rolling compression wheel contacting thelaminator strip/seam region is greater than or equal to the laminatorstrip width, the lines of compressive contact force generated aresubstantially perpendicular to the seam length and of infinite number.This achieves substantially complete seam overcoating/laminationprocessing with seam smoothing, stress-release, and substantialreduction of physical discontinuities of the entire seam region.Therefore, it is preferable that the line of compressive contact made bythe compression wheel 108 on the laminator strip 32 form an arc ofsufficient length to cover the full width of the laminator strip 32. Thecircumferential concave surface of the compression wheel 108 preferablygenerates a uniform linear compression force of, for example, betweenabout 1 lb/in (0.18 kilograms/cm) and about 20 lbs/in (3.6 kilograms/cm)when in rolling contact with the laminator strip 32. By comparison, if acompression wheel 108 having a peripheral surface with a cross sectionhaving an infinite radius of curvature (which is essentially a straightline) is used, only point contact is achieved since support membersurface is arcuate. The compression wheel 108 can be of any suitablematerial, including, for example, metallic, hard plastic, or compositematerials having a smooth contacting surface. It is preferred that thecontacting surface comprises a thin coating of low surface energymaterial, such as a fluoropolymer, such as Teflon, polysiloxane, apolyimide, such as Kapton, and the like.

In the event that it is required to process a flexible imaging memberhaving a slanted seam (i.e. a seam that is an angle other than 90degrees with each edge of belt 10), the integral part of heating source103 and compression wheel assembly may be programmed or set to preciselytrack the seam when traversing the entire belt width. However, it ispreferred that the belt be cocked and adjusted so that the seam isparallel to an imaginary axis of the support cylinder member (i.e.,without skewing) along the top of the support cylinder member after beltmounting.

Although the IR heat source 103 is shown as a quartz halogen lamp inFIG. 7, any other suitable source of heat energy can be used as the IRheat source 103. For example, embodiments can use an IR laser, such as asealed carbon dioxide (CO₂) laser, as the IR heat source 103, as isillustrated, for example, in FIG. 8. Sealed carbon dioxide (CO₂) lasersare commercially available, such as a Model Diamond 64 sealed carbondioxide laser from Coherent, Inc., which is a slab laser comprising apair of spaced apart, planar electrodes having opposed light reflectingsurfaces. The spacing of the electrodes is arranged such that light willbe guided in a plane perpendicular to the reflecting surfaces, whilelight in a plane parallel to the light reflecting surfaces is allowed topropagate in free space and is only confined by a resonator. Preferably,the lasing medium is a standard CO₂ lasing mixture, including, forexample, helium, nitrogen, and carbon dioxide with a 3:1:1 ratio, plusthe addition of five per cent xenon. The gas is maintained between 50and 110 torr and preferably on the order of about 80 torr. The gas iselectrically excited by coupling a radio frequency generator between theelectrodes, as is explained in the description of a typical sealedcarbon dioxide laser found, for example, in U.S. Pat. No. 5,123,028, theentire disclosure of which is incorporated herein by reference. Sealedcarbon dioxide lasers are also described in U.S. Pat. Nos. 5,353,297,5,353,297, and 5,578,227, the entire disclosures of which are alsoincorporated herein by reference. While such sealed carbon dioxidelasers can produce, for example, a 150 watt beam, when used inembodiments, such lasers should be adjusted to deliver a lower outputof, for example, about 6 watts for the seam heat treatment process.

Optics are employed in embodiments to treat the output of the laser. Aphase shift mirror can be used to transform a laser beam with linearpolarization into a beam with circular polarization. To obtain acircularly polarized beam, a phase shift mirror is positioned with anincidence angle of 45 degrees and the laser beam output with a plane ofpolarization parallel to the laser base is rotated 45 degrees to theplane of incidence. The resulting circularly polarized beam of heatenergy is focused with a lens into a desired size on the outer surfaceof the seam. For example, a Melles Griot Zinc Selenide Positive Lenswith focal distance of 63.5 mm (2.5 inches) can be used as the imagelens. In the process of the present invention, all of the radiant energyemission from the carbon dioxide laser 103 progressively strikeslocalized sites encompassing the seam and regions of the imaging beltimmediately adjacent the seam to deliver instant heating followed byquick cooling as the belt 10 with the supporting cylindrical 90 istraversed by the beam of heat energy from the laser heating source.

Preferably, the raw laser heat energy beam emitted from a laser has acircular cross section, but any other suitable cross sectional shape canbe used to raise the temperature of a localized site along the seam. Thediameter of a raw beam emitted by a laser is normally constant along theentire length of the beam. The thermal energy radiation emitted from acarbon dioxide laser is directed at the seam of the belt and the thermalenergy radiation from the laser forms a localized site, such as a roundspot, straddling the seam during traverse of the seam. The heatedlocalized site, such as a round spot, on the surface of the seampreferably has an average width of between about 3 millimeters and about25 millimeters measured in a direction perpendicular to the imaginarycenterline of the seam, depending upon the particular dimensions of theseam to be treated. For example, a Model Diamond 64 sealed carbondioxide laser from Coherent, Inc., has a circular raw heat energy beamhaving a diameter of about 6 millimeters. This raw laser heat energybeam will form a heated localized site or spot having a diameter ofabout 6 millimeters on the belt seam. If desired, the 6 millimeter spotsize of the thermal energy striking the outer surface of the seam can bereduced for small seam area heating by masking the emitted raw laserheat energy beam using any suitable device, such as a metal template, togive a 3 millimeter to 6 millimeter heated localized spot size measuredin a direction perpendicular to the imaginary centerline of the seam.Although the template can alter the heated localized spot shape to anysuitable and desired shape such as an oval, square, rectangle, hexagon,octagon and the like, a circular heated localized site or spot ispreferred. Moreover, where for example, the laser heat energy beam has adiameter of about 6 millimeters and a larger heat spot is desired on theouter surface of the belt seam, the laser beam can be defocused usingany suitable device, such as a zinc selenide lens between the laser beamsource and the belt seam. Thus, by varying the relative distancesbetween the laser beam source, the lens and the belt seam, the 6millimeter diameter laser beam can be defocused to give a larger spothaving a diameter greater than about 6 millimeters and preferably lessthan about 25 millimeters in diameter measured in a directionperpendicular to the imaginary centerline of the seam for stress releasetreatment of large seam areas. If a mask is employed to change the shapeof the raw laser heat energy beam or the defocused heat energy beam toform a spot shape other than round, the preferred heated localized siteor spot size that straddles the seam has an average diameter betweenabout 3 millimeters and about 25 millimeters measured in a directionperpendicular to the imaginary centerline of the seam. When the averagediameter of the heated localized site measured in a directionperpendicular to the imaginary centerline of the seam is less than about3 millimeters, the resulting stress release area is not enough to covera seam region which has a width of about 3 millimeters from one side ofthe seam region to the other. When the average diameter of the heatedspot is greater than about 25 millimeters, the stress release areaexceeds the intended seam treatment region and extends into theelectrophotographic imaging zone of the belt normally used for imageformation.

Since the carbon dioxide laser delivers a constant diameter raw heatenergy beam, the physical distance from the seam surface of the imagingbelt to the laser is less important for the heat treatment process ofthis invention, as long as the intended seam heat treatment spot size isthe same as the diameter of the raw laser beam or smaller than the rawlaser beam by using a masking template, the carbon dioxide laser spotsubstantially instantaneously elevates the temperature of polymermaterial in only a small localized region or site of the imaging layerof the imaging member above the glass transition temperature (T_(g)).Although the thermoplastic polymer material must be heated to at leastthe glass transition temperature thereof, such heated polymer materialneed be only in the upper portion of the seam area to achieve the seamtreatment objectives of this invention. However, if desired, heating ofthe seam region completely through the thickness or cross-sectionthereof can be accomplished during heating of a localized site.Elevation of the temperature of only a small localized region or sitealong the seam from one edge of the belt to the other to at least theglass transition temperature of the thermoplastic polymer material isaccomplished progressively as the heat energy beam traverses the widthof the belt along the seam.

An alternative heat source, a variation of that shown in FIG. 7, employsan elongated focused IR emitting source that can include, for example,an elongated halogen quartz tube coupled with a hemi-ellipsodal shapedcross-section elongated reflector. The elongated focused IR emittingsource is positioned above the seam laminator strip and covers theentire width of the imaging member 10. The elongated focused IR sourcethus delivers an IR focused heating line to heat the entire laminatorstrip 32 and seam 30 at once. The width of the focused IR heating lineshould cover the width of the laminate 34 of the laminator strip 32. Theheated strip and seam can then be compressed, as with a rolling wheel108 (or a heated rolling wheel 115 according to that shown in FIG. 9),while the belt 10 is belt down over the arcuate convex surface of tube90, to complete the seam overcoating/lamination treatment. Such afocused IR heating line can also be used in embodiments according to theprocess and apparatus of FIG. 6 where an externally-heated or coldcompression rolling wheel 150 is used, while belt 10 is held down overthe surface of flat support 148.

FIG. 9 illustrates another alternative embodiment of seamovercoating/lamination process and apparatus similar to that shown inFIG. 7. A single, internally-heated compression wheel 115 is employed toheat and compress the seam 30 of a belt 10 situated and held down withvacuum on an elongated support tube 90. The peripheral surface of wheel115 has an arcuate concave cross section having a curvature whichcorresponds to or is slightly larger than the curvature of the arcuateconvex surface of the elongated surface of the upper half of supporttube 90. This peripheral wheel surface should be maintained at atemperature sufficient to raise the temperature of the thermoplasticmaterial in at least the upper half of the belt seam to its glasstransition temperature T_(g). The peripheral surface of wheel 115 alsopreferably has a thin coating surface of abhesive material, such as afluoropolymer, such as Teflon, and the like to prevent imaging layermaterial from adhering to the wheel surface during the seam treatmentprocess. The heated compression wheel 115 is preferably metallic with asmooth peripheral surface. Heating of the wheel can be accomplished byany suitable device such as, for example, by an electromagnetic heatingmechanism 116 to give the desired temperature when wheel 115 traversesthe width of belt 10 along on the seam 30. Alternatively, any othersuitable device, such as a resistance wire heating system 117 can beemployed to heat compression wheel 115. Where the resistance wire ispart of the wheel, any suitable electrical connection such as slip rings118 can be used to provide electrical energy to the resistance wires.Sufficient heat energy should be supplied to wheel 115 to adequatelyheat the peripheral surface thereof. Preferably, the hot rotatablecompression wheel 115 is not reciprocated and the support tube 90carrying belt 10 is moved during the seam treatment. However, ifdesired, the support tube and belt can be stationary and the wheelreciprocated or both can be reciprocated to achieve relative motion witheach other.

Thus, the process and apparatus of embodiments as shown in the examplesdescribed above produce a flexible imaging member in which the seam hasa protective overcoating substantially free of protrusions, a smoothsurface profile, and that exhibits good physical continuity.Additionally, the seam area produced by embodiments has reduced seamarea thickness and enjoys reduced fatigue induced bending seam stresscracking under dynamic belt flexing conditions over the rollers a beltsupport module during imaging machine operation. Furthermore, treatingaccording to embodiments can substantially enhance imaging memberproduction yield, effectively reducing the belt unit manufacturing cost.Because successful implementation of embodiments greatly reduces ofsubstantially eliminates the need of labor-intensive and time-consumingmanual seam inspection procedures, embodiments also effectively increaseproduction belt yield by recovery of those belts that are otherwise lostas rejects due to the presence of seam protrusions. Thus, embodimentsdeliver a seam configuration with significantly improved qualities,better physical/mechanical attributes, such as smoother surface profile,absence of protrusion spots, thinner cross-section thickness, and littleor no physical discontinuity to enhance cleaning blade performance andsuppress the premature onset of fatigue induced seamcracking/delamination problem during extended electrophotographicimaging and cleaning processes.

It should be noted that, though embodiments use a treatment article orstrip with the thermoplastic polymer film on a carrier/supportsubstrate, such as that shown in FIG. 4, the present invention can beperformed with a treatment article or strip including a single layer ofthermoplastic polymer with no carrier/support substrate. A number ofexamples are set forth hereinbelow and are illustrative of differentcompositions and conditions that can be used in practicing embodiments.All proportions are by weight unless otherwise indicated, are exemplaryin nature, and are not limiting to the invention. It will be apparentthat the invention can be practiced with many types of compositions andcan have many different uses in accordance with the disclosure above andas pointed out hereinafter.

EXAMPLE 1 Belt Preparation

An electrophotographic imaging member web was prepared by providing aroll of titanium-coated, biaxially-oriented thermoplastic polyestersubstrate. The substrate comprised PET, Melinex (available from ICIAmericas, Inc.) and had a thickness of 3 mils (76.2 micrometers). Ablocking layer with a dry thickness of 0.05 micrometer was formed on thesubstrate, on which an adhesive interface layer was then prepared with adry thickness of 0.07 micrometer. The adhesive interface layer wasthereafter coated with a photogenerating layer with a dry thickness of2.0 micrometers. However, a strip about 3 mm wide along one edge of thecoating web, having the blocking layer and adhesive layer, wasdeliberately left uncoated by any of the photogenerating layer materialto facilitate adequate electrical contact with the ground strip layerthat is applied later. Next, a charge transport layer and a ground striplayer were applied by co-extrusion of the coating materials. Theuncoated portion of the adhesive layer was included in the applicationof the ground strip layer. Finally, an anti-curl coating was applied tothe rear surface (side opposite the photogenerator layer and chargetransport layer) of the electrophotographic imaging member web toproduce a dried coating layer having a thickness of 13.5 micrometers.

The charge transport layer was prepared by introducing into an amberglass bottle in a weight ratio of 1:1 (or 50% wt of each)N,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine andMakrolon 5705, a Bisphenol A polycarbonate thermoplastic having amolecular weight of about 120,000 commercially available fromFarbensabricken Bayer A.G. The resulting mixture was dissolved to give15 percent by weight solid in methylene chloride. This solution wasapplied on the photogenerator layer by extrusion to form a coating whichupon drying gave a thickness of 24 micrometers.

The prepared electrophotographic imaging member web had a width of 353millimeters and was cut to provide five rectangular sheets each 559.5millimeters in length for flexible imaging member seaming operation. Theopposite ends of each imaging member were overlapped 1 mm and joined byan ultrasonic energy seam welding process using a 40 Khz horn frequencyto form a seamed electrophotographic imaging member, having a top seamsplashing surface morphology 74 and displaying a physical discontinuitystep 72 with a junction point 76 according to the illustration in FIG.2. Four of the five seamed belts were ready to be used for inventionseam overcoationg/lamination processing while one of the remainingunprocessed seamed belt was used to serve as a control.

EXAMPLE II Treatment Article Preparation and Application; No Substrate

Six thermoplastic polymercoating solutions were prepared by dissolvingMakrolon 5705 polycarbonate with varying amount of charge transportcompoundN,N′-diphenyl-N,N′-bis(3-methylphenyl)-1,1′-biphenyl-4,4′-diamine inmethylene chloride. The prepared solutions were each applied over areleasing substrate and dried at 257° F. (125° C.) in an air circulatingoven for 5 minutes to rid the solvent and then removed from the releasesubstrates to give thermoplastic polymer layers containing 0% wt, 10%wt, 20% wt, 30% wt, 40% wt, and 50% wt charge transport compound in eachrespective 25 micrometer thick layer. The thermoplastic polymer layerswere each analyzed for glass transition temperature, T_(g), usingdifferential scanning calorimetric method. The results obtained, listedin the table below, showed that the addition of charge transportcompound to the Makrolon could provide successive suppression of theT_(g) of the resulting polymer layer:

[Glass Transition Temperature for % wt] POLYMER LAYER T_(g) (° C.)  0%wt 156 10% wt 135 20% wt 120 30% wt 104 40% wt 91 50% wt 84

A 5 mm width strip was cut from the thermoplastic polymer layercontaining 50% by weight charge transport compound (essentiallyidentical to the charge transport layer of the electrophotographicimaging member of Example I) and placed over the top seam splash 68(refer to seam morphology description in FIG. 2) of one weldedelectrophotographic imaging member of Example I, which was vacuum helddown, to overcoat/laminate the seam region by heat and compressionprocessing as that in FIG. 5. The compression pressure exerted by thehot compression bar was approximately 200 lbs/in² and with a temperatureof about 130° C. to effect the seam overcoating/lamination outcome.

Since the processing was carried out at a temperature 46° C. above theT_(g), the overcoat laminate became compressible as well as malleableunder the applied pressure to readily fuse onto the seam and fill-up theseam step junction 76.

EXAMPLE III Treatment Article Prepration and Application, Substrate

A coating solution, prepared by dissolving 10 grams of Makrolon in 90grams of solvent mixture consisting of 90 parts of methylene chlorideand 10 parts of toluene, was applied to a 3-mil thick,biaxially-oriented PET substrate by hand coating using a Birdapplicator. The coated wet Makrolon layer was allowed to dry under roomambient conditions for 15 hours to produce a 35-micrometer thick solidpolymer layer containing 60% by weight Makrolon and approximately 40% byweight toluene, with only a small amount of residual methylene chloridesince toluene was much less volatile than methylene chloride. Theresulting coating layer over PET substrate was cut to give an 8 mm widthstrip. The coating layer in this 8 mm strip was cut at both sides,through only the Makrolon layer not the PET, to remove 2 mm of Makroloncoating layer from each side to create a laminator strip 32, like thatillustrated in FIG. 4, which consists of a 4 mm width thermoplasticpolymer laminate 34 adhered onto an 8 mm wide flexible PET carriersubstrate 36.

The fabricated laminator strip 32 was positioned over the seam of thesecond welded electrophotographic imaging member of Example I and thensubjected to the inventive seam overcoating/lamination processing,carried out with the same procedures and apparatus as described inExample II. Since the laminate strip 34 was loosely adhered to the PETcarrier substrate 36 (only about 6 grams/cm 180° peel strength), it waseasily removed from the seam overcoat after completion of theheat/compression application. The resulting overcoated seam had beenfound to obtain about equivalent physical and morphological attributeimprovements seen in the treated seam of Example II.

EXAMPLE IV Treatment Article Preparation & Application, Solution ofExample II on Substrate; IR Lamp and Wheel on Tube

A laminator strip 32 was prepared, using a coating solution according toExample II and a 3-mil thick biaxially oriented PET substrate, accordingto the procedures described in Example III, to give a 25-micrometerthick polymer laminate 34, containing 70% by weight Makrolon and 30% byweight charge transport compound, over PET carrier substrate 36. Thesurface of laminate 34 of the prepared laminator strip 32 was firstbrushed (using a small soft paint brush) with small amount of methylenechloride to moisten the surface and thereby promote some adhesion to theseam region surface for ease of anchoring the laminator strip 32directly onto the seam of the third welded electrophotographic imagingmember of Example I, which was held down over a 2-inch diameter tube 90as illustrated in FIG. 7. The overcoating/lamination processing used anIR heat source 103 to provide a focused, 8 mm diameter hot spot forlocalized heating of the laminator strip 32 to a temperature of 120° C.The hot spot was followed with a free rotating compression wheel 108 togenerate an 8 lbs/in compression line for effective seamovercoating/lamination result.

The heating and compression procedures to achieve the invention seamovercoating/lamination result were carried out according to embodimentssuch as that illustrated in FIG. 7 and given in the preceding text ofthis specification. Since the laminate 34 was loosely adhered to the PETcarrier substrate 36, the PET was readily peeled off from the overcoatedseam after the processing.

EXAMPLE V Treatment Article Preparation and Application TreatmentArticle of Example IV; IR Laser and Wheel on Tube

A laminator strip 32 was again prepared, in exact same manners describedin Example IV, to give a laminate 34 having 25 micrometers in thicknessand containing 30% by weight charge transport compound over PET carriersubstrate 36.

To effect invention seam treatment processing, the fourth weldedelectrophotographic imaging member 10 of Example I was suspended (asshown in the illustration of FIG. 7) over a horizontally movablecantilevered supporting aluminum tube 90, having a 2-inch (5.08centimeters) diameter, a wall thickness of about 0.25 inch (6.35millimeters), and an anodized outer surface, with the welded seam 30parked directly along the top (i.e. 12 o″clock position) of the supporttube 10 and being parallel to the axis of the tube. The tube 10contained a pair of slots 10, with one slot at the 9 o″clock positionand the other at the 3 o″clock position. Each slot extended along thelength of the imaging member width and was 2 millimeters wide. The freeend of the tube 10 was sealed by a cap and the supported end wasconnected to a flexible hose leading through a valve to a vacuum source.The vacuum source was maintained at a pressure of about 40 mm Hg. Thebelt in the seam area was held down against the upper arcuate convexsurface of the supporting tube when the valve to the vacuum source wasopened so that the seam area conformed to the shape of the upper surfaceof the tube. The laminator strip 32, having the surface of the laminate34 moistened with methylene chloride was placed directly over the seamgive some adhesion hold down onto the seam region for ease of carryingout the heat/compression seam lamination process. The temperature of alocalized circular spot, about 8 mm in diameter, of the laminator strip32 and the respective covering seam region was raised to about 120° C.using a sealed carbon dioxide laser heating source 103 (Model Diamond64, available from Coherent, Inc.) instead of the focused IR of ExampleIV. The laser heat source 103 had an adjacent trailing free rotatingcompression wheel attachment, as shown in FIG. 8, which was adjustableto deliver an about 8 lbs/cm compresion line over the heat spot byspring 110, to effect the heat/compression process.

This invention seam treatment processing was then carried out accordingto the schematic illustration of FIG. 7. The carbon dioxide laserheating source had a 150 wattage power capability, but for the purposeof present seam treatment process, it was adjusted to deliver an energyoutput of only about 5.6 watts at an 8 millimeter diameter of raw laserbeam spot. An infrared sensing camera was employed to adjust laserdelivery of 150 Hz, 50 microsecond pulse duration, and a seam traversingspeed of 2 in/s (5.08 cm/s) to ensure that the heat spot on laminatorstrip for seam treatment temperature reached 120° C. A spot temperatureof 120° C. was sufficient to soften the laminate 34 and the chargetransport layer beneath the laminate 34 for effectual application of theovercoating laminate to smooth out surface profile, fill the seam splashjunction 76 to thereby eliminate the physical discontinuity, and yieldseam stress-release result. The laser heat source emitted a dominantradiant wavelength of 10.64 micrometers and formed a substantiallycircular laser spot of about 8 mm in diameter incident over andstraddling the laminator strip and seam area to provide instant heatingresult in the localized site to effect such heating progressing alongthe length of the seam, as the support tube 90 with the held down belt10 were moved under the laser heat source/compression wheel assembly ata traversal speed of 2 in/s (5.08 cm/s) and exerting about 20 pounds ofrotating wheel compression force by the spring 110 to yield a 4 mm linecontact over the laminator strip and the covering seam region;accordingly, the rotating wheel generated an compression line force ofabout 8 lb/cm linear width. The entire seam heat/compression andovercoating/lamination processing carried out for each imaging memberwas completed in about seven seconds.

EXAMPLE VI

The invention seam overcoating/lamination processing carried out for theseamed electrophotographic imaging member belts described in Examples IIto V was seen to give overcoat laminate that was strongly bonded to thewelded seam region, since the laminate used was essentially made of thesame materials and chemical components of the seam. Therefore, the endresult of the seam overcoating/lamination was that the laminate wasfused onto the seam area and became an integral part of the seam, whicheliminated the physical discontinuity to display a tapering surfacetopology without the seam splash junction 76. Further seam surfaceroughness analysis of these seamed belts before and after treatment,using a Wyko Gauge surface analyzer, showed that the original seamsplash surface roughness was significantly reduced from an average highRa value of 6.3 to a low value of 1.6. The inventive treatment processwas also found to produce a slight overall reduction in seam areathickness of up to about 10 percent.

The control electrophotographic imaging member of Example I and the fourseam overcoated electrophotographic imaging members obtained through thetreatment process of the present invention described by Examples II to Vwere each dynamically cycled and print tested in a xerographic machine,having a belt support module comprising a 25.24 mm diameter driveroller, a 25.24 mm diameter stripper roller, and a 29.48 mm diametertension roller to exert on each belt a tension of 1.1 pounds per inch.The belt cycling speed was set at 65 prints per minute.

The control imaging member of Example I, having no seam overcoatlaminate, was cyclic tested to only about 56,000 prints and terminatedfor the reason of developing onset of seam cracking/delaminationproblem.

When the very same belt cycling procedure was repeated with each of theimaging members through the process of the present invention, neitherseam failure nor notable ripple appearance in the image zones wereobserved after completion of 500,000 prints of belt cyclic testing.Further, minimal cleaning blade wear was observed after completion of500,000 prints of belt cyclic testing.

In recapitulation, the seam overcoating/lamination process of thepresent invention resolves seam cracking/delamination problems, providesa very short treatment processing cycle time, substantially eliminatesseam splash junction physical discontinuity, substantially prevents theappearance of ripples in the imaging zones adjacent to the seam heattreatment area, provides smoother surface profiles, producesdimensionally stable imaging members, suppresses cleaning blade wear,and yields a processed seam substantially free of high protrusion spotsto thereby reduce seamed imaging member rejection rates, which increasesimaging member production yield.

Although the invention has been described with reference to specificexemplary embodiments, it is not intended to be limited thereto. Rather,those having ordinary skill in the art will recognize that variationsand modifications may be made therein which are within the spirit of theinvention and within the scope of the claims.

1. A flexible belt seam treatment apparatus comprising: a supportelement with a smooth, abhesive surface that includes a fluoropolymer,the fluoropolymer arranged to support a belt seam region; a heat sourcecomprising an infrared radiation source in optical communication withoptics that form a heat spot across at least a portion of a treatmentstrip and at least a portion of a belt seam region on which thetreatment strip is placed; and a pressure applicator arranged to forceat least the portion of the treatment strip against the portion of thebelt seam region.
 2. The apparatus of claim 1 wherein the pressureapplicator exerts about 1 lb/in to about 20 lb/in line contact force. 3.A belt seam treatment apparatus comprising: a tube with a smooth,abhesive outer surface; a belt hold system arranged to hold a seamregion of a belt against at least a portion of the outer surface of thetube, wherein the belt hold system includes a bar that extends through aportion of the belt farthest from the tube and selectively pulls thebelt against the tube; an infrared lamp in optical communication withthe at least a portion of the outer surface of the tube against whichthe seam region of the belt is held; optics that reflect and focus theinfrared radiation from the infrared lamp onto at least a portion of theseam region of the belt after a treatment strip has been applied whereinthe lamp extends across substantially the entire seam region and theoptics form a heat line across the entire seam region; and a pressurewheel with a substantially concave outer surface substantiallycorresponding to a curvature of the at least a portion of the outersurface of the tube against which the seem region of the belt is held.4. The apparatus of claim 3 wherein the optics form a heat spot on aportion of the strip and the seam region and further comprising anactuator that adjusts the optics so that the heat spot traverses a widthof the seam region.
 5. The apparatus of claim 4 further comprisinganother actuator that moves the pressure wheel with the heat spot tocompress a portion of the strip and the seam region that the heat spothas heated.
 6. The apparatus of claim 3 wherein the belt hold systemcomprises a vacuum system including at least one opening in the outersurface of the tube, a sealed end of the tube, and an unsealed end ofthe tube in selective fluid communication with a vacuum source.
 7. Aflexible bell seam treatment apparatus comprising: a substantiallyplanar support element with a smooth surface arranged to support a beltseam region; a heat source comprising an infrared radiation source inoptical communication with optics that form a heat spot across at leasta portion of a treatment strip and at least a portion of a belt seamregion or which the treatment strip is placed; and a pressure applicatorincluding a pressure wheel having a substantially right cylindricalouter surface, the applicator arranged to force at least the portion ofthe treatment strip against the portion of the belt seam region.
 8. Theapparatus of claim 7 wherein an outer surface of the pressure wheelcomprises an abhesive coating.
 9. A belt seam treatment apparatuscomprising: a tube with a smooth, abhesive outer surface; a belt holdsystem arranged to hold a seam region of a belt against at least aportion of the outer surface of the tube, wherein the belt hold systemincludes a bar that extends through a portion of the belt farthest fromthe tube and selectively pulls the belt against the tube; an infraredradiation source in optical communication with the at least a portion ofthe outer surface of the tube against which the seam region of the beltis held; and a pressure wheel with a substantially concave outer surfacesubstantially corresponding to a curvature of the at least a portion ofthe outer surface of the tube against which the seam region of the beltis held.
 10. The apparatus of claim 9 wherein the infrared radiationsource is an infrared laser.
 11. The apparatus of claim 10 furthercomprising optics that alter a polarization of infrared radiation fromthe infrared laser and form a heat spot on a portion of the seam regionof the belt after the treatment strip has been applied.
 12. Theapparatus of claim 11 further comprising an actuator that adjusts theoptics so that the heat spot traverses a width of the seam region. 13.The apparatus of claim 12 further comprising another actuator that movesthe pressure wheel with the heat spot to compress a portion of the stripand the seam region that the heat spot has heated.
 14. The apparatus ofclaim 9 wherein the bar is connected to an actuator that selectivelyexerts force on the belt to pull the belt against the tube.
 15. Theapparatus of claim 9 wherein the bar is placed in the belt by anoperator and pulls the belt through the action of gravity on the bar.